No abstract

We measured the cobalt and chromium concentrations in the serum and urine of 32 patients with current designed metal-on-metal total hip arthroplasty and 43 patients with conventional metal on ultrahigh molecular weight polyethylene (UHMWPE) cementless total hip arthroplasty. The results of our study showed that the serum and urine chromium concentrations increased in 37.5% and 90.6%, respectively, of 32 patients with well-fixed metal articulation (the mean values were 0.09 microg/dl and 2.2 microg/l, respectively) and also increased in 28.6% and 85.7%, respectively, of 7 patients who received metal-on-UHMWPE articulation with loosened acetabular component or stem made of Co/Cr alloy (the mean values were 0.06 microg/dl and 1.6 microg/l, respectively). On the other hand, the serum and urine cobalt concentrations were below the detection limit in all patients.

The operative procedures chosen for arthrosis with severe acetabular dysplasia vary among orthopaedic surgeons. We operated on 250 hips using the rotational acetabular osteotomy (RAO) method of Ninomiya and Tagawa [8]. In this report, we describe the technique of RAO and the results of this procedure in patients with severely dysplastic hips. Among the 250 hips, there were 6 which were classified as Severin group V. In those hips, the CE angle was less than 0 degrees, and the femoral head showed superolateral subluxation. After acetabular osteotomy with straight and curved osteotomes, smooth inferolateral rotation could be done in all cases. At the latest follow-up symptoms were improved remarkably, especially pain. Radiographically, adequate coverage of the femoral head was achieved and joint congruence improved in all 6 hips.

No abstract

This retrospective case series enrolled 13 patients who underwent posterior fixation with both transdiscal screws for diffuse idiopathic skeletal hyperostosis (TSDs) and pedicle screws (PSs) to treat spinal injury accompanied by diffuse idiopathic skeletal hyperostosis (DISH). Purpose: To describe the usefulness, feasibility, and biomechanics of TSD. Overview of Literature: Vertebral bodies accompanied by DISH generally have lower bone mineral density than normal vertebral bodies because of the stress shielding effect. This phenomenon tends to makes screw fixation challenging. To our knowledge, solutions for this issue have not previously been reported. Methods: Patients were assessed using the data on surgical time, estimated intraoperative blood loss, mean number of stabilized intervertebral segments, number of screws used, perioperative complications, union rate, and the three-level EuroQol five-dimensional questionnaire (EQ5D-3L) score at the final follow-up. The Hounsfield unit (HU) values of the screw trajectory area, and the actual intraoperative screw insertion torque of TSDs and PSs were also analyzed and compared. Results: The surgical time and estimated intraoperative blood loss were 165.9±45.5 minutes and 71.0±53.4 mL, respectively. The mean number of stabilized intervertebral segments was 4.6±1.0. The number of screws used was 4.9±1.3 for TSDs and 3.0±1.4 for PSs. One death occurred after surgery. The union rate and EQ5D-3L scores were 100% and 0.608±0.128, respectively. The HU value and actual intraoperative screw insertion torque of TSDs were significantly better than those of PSs (p<0.001, p=0.033). Conclusions: We were able to achieve stable surgical outcomes using the combination of TSDs and PSs. The HU value and actual intraoperative screw insertion torque were significantly higher for TSDs than for PSs. Based on these results, when treating thoracolumbar spinal fractures accompanied by DISH in elderly populations, the TSD could be a stronger anchor than the PS.